The Human Islet Isolation Core Facility (HIICF) of the Washington University Diabetes Research and Training Center (DRTC) sup;lies fresh, frozen and cryopreserved human pancreatic islets to NIH funded investigators conducting diabetes research at Washington University as well as to other investigators in North America. This Core was first established in 1987 and recommended for support for three years. In 1990 it was re-evaluated by an ad hoc NIH review group and recommended for two additional years of funding. The main mission of the HIICF is to support high quality research in diabetes. During its first four years this Core supplied human islets to 30 NIH supported investigators who have published over 40 original research papers in high quality, peer reviewed journals in work ranging from clinical and basic transplant immunology, the molecular biology of insulin secretion and islet glucose transporters, the islet antigens associated with the GAD protein and IDDM, and islet electro physiology. the HIICF also supports the training of established investigators, post doctoral fellows and graduate students in all aspects of human islet isolation: purification, culture, cryopreservation and transplantation. In the first four years 28 established investigators from all over the world and 19 graduate students and fellows have been trained in this core. Although the Human Islet Transplantation Research Program benefits from the existence of the Core, the costs of processing islets for human transplantation are not charged to this DRTC Core. With continued improvements in the collection, processing and cryopreservation of human islets this facility will develop further as a vital, unique and cost effective resource to DRTC investigators at Washington University and diabetes investigators at other institutions.